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I think both NEC and CEC align on this.

A "Neutral" is not counted as a CCC, but the "identified" conductor is (The grounded conductor in the NEC)
Now I am confused. In a typical installation, I thought the neutral is the grounded conductor also the " identified conductor". The neutral, or grounded conductor in RLC circuits or supplied from a 3 phase 208/120 system is a current carrying conductor. If it is only a 120 volt circuit then it is a current carrying conductor. If it only carries the unbalanced load of a resistive multiwire circuit then it might not be a current carrying conductor.
 

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I think both NEC and CEC align on this.

A "Neutral" is not counted as a CCC, but the "identified" conductor is (The grounded conductor in the NEC)
I believe 'identified' is used in a broader scope. It may or may not be a CCC depending on the context; it's the white wire. Take for example single-phase apartments on a 3phase service. The identified in each suite's feeder is current-carrying any time the suite is energized. The identified in each riser to the meter stack is not considered current-carrying for de-rating (i.e. in conduit.)
 

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I think the two Canadian’s and Dennis are right on. In you typical feeder or service entrance, whether it’s single phase 3-wire or three phase 4-wire, the neutral is not a current carrying conductor for derating. Yes it Carrie’s current, the unbalanced load. But for heat and derating, it’s only going to give off the heat that’s missing in the un-grounded conductors. So the conduit will never see more heat than what the (3) three phase conductors would give off.

The same would go for multiwire branch circuits utilizing all the phase conductors along with the neutral/grounded/identified conductor.

Your typical two wire circuit or two phases and a neutral of a three phase system, the neutral would count as a current carrying conductor. It will give off heat just like the phase conductors in this situation.

I don’t ever figure in harmonics. It’s not all it’s cracked up to be.
 

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I think both NEC and CEC align on this.

A "Neutral" is not counted as a CCC, but the "identified" conductor is not always a "Neutral" (The grounded conductor in the NEC)
Now I am confused. In a typical installation, I thought the neutral is the grounded conductor also the " identified conductor". The neutral, or grounded conductor in RLC circuits or supplied from a 3 phase 208/120 system is a current carrying conductor. If it is only a 120 volt circuit then it is a current carrying conductor. If it only carries the unbalanced load of a resistive multiwire circuit then it might not be a current carrying conductor.
Sorry to confuse ... would help if I finished my sentences!
 

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Due Dilligence: OK, I've checked Article 100, Googled it and checked here on Electrician Talk as well, and it's still not absolutely clear to me (and apparently others) whether the neutral is considered Current Carrying. Some key points I've found are:
  • It does carry current, but is not current carrying conductor (or something like that),
  • and, Yes it is a Current Carrying Conductor, but doesn't always carry current,
  • there are many references to NEC 310.15(B)(4)...which doesn't exist anymore...Whatever.
I'm neck deep in studying Table 310.16 (through Jade Learning, which is excellent), and the values for allowable ampacity need to be modified for conditions such as ambient temperature, number of conductors in a raceway or cable, or other conditions of use. And, as many others say..."it's clear as mud" whether NEC considers the neutral to be a Current Carrying Conductor.

What say you all?

Edit: I just found it in the 2020 NEC Handbook. Section 310.15(E) reminds us that neutral conductors in some cases, is NOT considered current carrying. From where I'm standing, it looks like in all cases but one, is the neutral considered current carrying.

310.15(E) Neutral Conductor. Neutral conductors shall be considered current carrying in accordance with any of the following:
  1. A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(C)(1).
  2. In a 3-wire circuit consisting of tho phase conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system, a common conductor carries approximately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying the provisions of 310.15(C)(1).
  3. On a 4-wire, 3-phase wye circuit where the major portion of load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor.
Additional Commentary text: Nonlinear loads on 3-phase circuits can cause an increase in neutral conductor current.
Here is a very simple test you can do to find out.
Use Telephone wire as neutral on a 10 Amp load stand back and watch it melt
 

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Don't let semantics get the better of you or you'll be running in circles chasing your tail.

"Current Carrying Conductor" is an odd term. "Conduct" means carry current. If a conductor doesn't carry current, why would it even be there?

Not counting the equipment grounding conductor / green wire in ampacity calculations is easy to understand - the equipment grounding conductor only carries current in fault conditions.

In multiwire circuits, there is a cancellation effect so the neutral may carry less current than the hots. If all the hots are fully loaded and perfectly balanced, the neutral carries zero. However also note that under other circumstances the neutral carries more than some of the hots. For example in a four wire multiwire branch circuit on a wye system you could have

load on A = 20A
load on B = 20A
load on C = 0A
load on N = 20A

The neutral is carrying current (full load in fact) and is carrying more than C hot.

Or you could have

load on A = 20A
load on B = 5A
load on C = 5A
load on N = 15A

The neutral is carrying current, and is carrying more than B or C hots.

(BTW, these examples are everyday occurrences. If you have a bank of cubicles in an office fed with a four wire 208/120 multiwire branch circuit, the receptacles in the cube base will be on one of the three phases. If one person plugs in a space heater to an A receptacle, and another plugs a space heater in a B receptacle, you'll have that loading above.)

You can play the values for A, B, and C on this graph

20A three phase MWBC neutral current (desmos.com)

and notice that no matter what you do, the biggest perimeter you could draw is the perimeter of an equilateral triangle with the side equal to the full capacity of the circuit. The perimeter of the triangle is the combined load on the four wires. So the maximum TOTAL load on the four wires is THREE times the full load of the circuit. So it makes sense to count these four wires as THREE for derating purposes, which are based on the combined load on the wires.

So they tell you that you don't have to count the neutral in your derating calculation, but it's not because the neutral doesn't carry current, it just works for making the calculations.
 

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So, just to be crystal clear, when dealing with Table 310.16 to determine conductors & ampacities, that the neutral is counted as a current carrying conductor. That it's one of the three, or when counted it adds up to more than three. Period. End of story. Pack up sh!t and go home. Correct?
Exactly.
Code requires, as written the why's and the what-for's that there are always at least TWO backups to the rules to eliminate, in as much as humanely possible, any cause for harm to people or structures.

That's the WHY.

If ya wanna what- for...

It's easier to just accept it.
 

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Now I am confused. In a typical installation, I thought the neutral is the grounded conductor also the " identified conductor". The neutral, or grounded conductor in RLC circuits or supplied from a 3 phase 208/120 system is a current carrying conductor. If it is only a 120 volt circuit then it is a current carrying conductor. If it only carries the unbalanced load of a resistive multiwire circuit then it might not be a current carrying conductor.

Technically the only way that a grounded conductor is a neutral is if the load is balanced and thus it is not considered a current carrying conductor. A grounded conductor is a neutral if it has 0 current.

On a single phase system the Neutral = A-B
If A is 15 amp and B is 15 amps then the grounded conductor is 0 amps and therefore a neutral. We use the term loosely and that is where the misunderstanding comes from.

If you have a single phase system and you share a neutral with A and B then the grounded conductor is not a current carrying conductor even though it may carry current.

Let suppose A and B are 20 amp circuits and for the sake of explaining this the maximum amps that will be seen with both A and B is 40 amps. If A = 15 amps and B = 20 amps then the grounded conductor will see 5 amps (20-15)... If you add those 3 up 15 + 20 + 5 = 40 amps.. With any combination you will never see more than 20 amps which can be counted on the A and B thus the grounded conductor is not counted because it doesn't add any more amps than A and B will carry.

I am sure an engineer would give me hell for that explanation but it always helped when I explained it to others.
 

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Technically the only way that a grounded conductor is a neutral is if the load is balanced and thus it is not considered a current carrying conductor. A grounded conductor is a neutral if it has 0 current.
From Article 100

Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions. (CMP-5)

Neutral Point. The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system. (CMP-5)

Informational Note: At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential
 

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Technically the only way that a grounded conductor is a neutral is if the load is balanced and thus it is not considered a current carrying conductor. A grounded conductor is a neutral if it has 0 current.

On a single phase system the Neutral = A-B
If A is 15 amp and B is 15 amps then the grounded conductor is 0 amps and therefore a neutral. We use the term loosely and that is where the misunderstanding comes from.

If you have a single phase system and you share a neutral with A and B then the grounded conductor is not a current carrying conductor even though it may carry current.

Let suppose A and B are 20 amp circuits and for the sake of explaining this the maximum amps that will be seen with both A and B is 40 amps. If A = 15 amps and B = 20 amps then the grounded conductor will see 5 amps (20-15)... If you add those 3 up 15 + 20 + 5 = 40 amps.. With any combination you will never see more than 20 amps which can be counted on the A and B thus the grounded conductor is not counted because it doesn't add any more amps than A and B will carry.

I am sure an engineer would give me hell for that explanation but it always helped when I explained it to others.
From Article 100

Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions. (CMP-5)

Neutral Point. The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system. (CMP-5)


Informational Note: At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential
So by definition the wire connected to the neutral point is a neutral conductor and could carry current. This is also the grounded conductor and the identified conductor. So with de-rating it should be counted.
 

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So by definition the wire connected to the neutral point is a neutral conductor and could carry current. This is also the grounded conductor and the identified conductor. So with de-rating it should be counted.

It depends. When there is a single phase situation then any 2 wire circuit would count the neutral as a current carrying conductor. If you had a multiwire branch circuit then no you don't count the neutral.

Same for 3 phase- if you have a neutral and one or two hot conductors then the neutral counts but if it was a full boat- 3 hots and one neutral then the neutral wouldn't count. Of course, I am using the neutral as most people do -- it is the same as the grounded conductor for most of us.
 

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Take look at how GFCI works. It measures the current flow imbalance between hot and neutral. If you have current flow in the hot wire (possibly to the ground fault) but no current in the neutral it will trigger.
 

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I don’t ever figure in harmonics. It’s not all it’s cracked up to be.
Ain't it the truth ?!?!?!?

I file that with the "super neutrals..." and "isolated grounds..."

Snake oil & great salesmanship.
Technically the only way that a grounded conductor is a neutral is if the load is balanced and thus it is not considered a current carrying conductor. A grounded conductor is a neutral if it has 0 current.

On a single phase system the Neutral = A-B
If A is 15 amp and B is 15 amps then the grounded conductor is 0 amps and therefore a neutral. We use the term loosely and that is where the misunderstanding comes from.

If you have a single phase system and you share a neutral with A and B then the grounded conductor is not a current carrying conductor even though it may carry current.

Let suppose A and B are 20 amp circuits and for the sake of explaining this the maximum amps that will be seen with both A and B is 40 amps. If A = 15 amps and B = 20 amps then the grounded conductor will see 5 amps (20-15)... If you add those 3 up 15 + 20 + 5 = 40 amps.. With any combination you will never see more than 20 amps which can be counted on the A and B thus the grounded conductor is not counted because it doesn't add any more amps than A and B will carry.

I am sure an engineer would give me hell for that explanation but it always helped when I explained it to others.
"Sounds good to me!!!" :p:sneaky: -Eric Cartmann from "South Park."
 

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Due Dilligence: OK, I've checked Article 100, Googled it and checked here on Electrician Talk as well, and it's still not absolutely clear to me (and apparently others) whether the neutral is considered Current Carrying. Some key points I've found are:
  • It does carry current, but is not current carrying conductor (or something like that),
  • and, Yes it is a Current Carrying Conductor, but doesn't always carry current,
  • there are many references to NEC 310.15(B)(4)...which doesn't exist anymore...Whatever.
I'm neck deep in studying Table 310.16 (through Jade Learning, which is excellent), and the values for allowable ampacity need to be modified for conditions such as ambient temperature, number of conductors in a raceway or cable, or other conditions of use. And, as many others say..."it's clear as mud" whether NEC considers the neutral to be a Current Carrying Conductor.

What say you all?

Edit: I just found it in the 2020 NEC Handbook. Section 310.15(E) reminds us that neutral conductors in some cases, is NOT considered current carrying. From where I'm standing, it looks like in all cases but one, is the neutral considered current carrying.

310.15(E) Neutral Conductor. Neutral conductors shall be considered current carrying in accordance with any of the following:
  1. A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(C)(1).
  2. In a 3-wire circuit consisting of tho phase conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system, a common conductor carries approximately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying the provisions of 310.15(C)(1).
  3. On a 4-wire, 3-phase wye circuit where the major portion of load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor.
Additional Commentary text: Nonlinear loads on 3-phase circuits can cause an increase in neutral conductor current.
The neutral is a current currying conductor, no question about it. There are applications where the neutral will not carry current for example when you feed a 3-phase motor from a WYE secondary transformer. You have to bring the 3 phase conductors, the neutral and the equipment grounding conductor to your first disconnect/over current protection device; however, after landing on the neutral bus, the neutral doesn't go anywhere else. Or if you have a three phase panel (with a neutral) with only 3-phase loads. The neutral is supposed to curry the unbalance on a system with 3-phase and single phase loads and in the ideal world the current on the neutral will be zero if the system is perfectly balanced, but this is just in the ideal world.
 

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I think the two Canadian’s and Dennis are right on. In you typical feeder or service entrance, whether it’s single phase 3-wire or three phase 4-wire, the neutral is not a current carrying conductor for derating. Yes it Carrie’s current, the unbalanced load. But for heat and derating, it’s only going to give off the heat that’s missing in the un-grounded conductors. So the conduit will never see more heat than what the (3) three phase conductors would give off.

The same would go for multiwire branch circuits utilizing all the phase conductors along with the neutral/grounded/identified conductor.

Your typical two wire circuit or two phases and a neutral of a three phase system, the neutral would count as a current carrying conductor. It will give off heat just like the phase conductors in this situation.

I don’t ever figure in harmonics. It’s not all it’s cracked up to be.
I like that explanation. However, here in Chattanooga the inspectors took a seminar and then declared that neutral conductors were always current carrying conductors unless we can prove that they carried no current beyond the unbalanced load in a multiphase circuit. Since I can almost never do that (how many devices today have zero nonlinear component even discounting capacitance and inductance? What about a couple decades from now?) and certainly don't want to spend my time doing that, I always count it in calculations. The only exception would be if I'd like to use an existing conduit and counting the neutral would make it be too small; then I might spend some time on loads if it seemed promising.

On the other hand, I have stopped oversizing neutrals. Back in the early days of switching power supplies and electronic ballasts it wasn't uncommon to see harmonics running near 50%, mostly in triplens, and thus three phases could easily overload a neutral to the point of fire. Today THD is seldom worse than 80% and in my opinion overloading is just not an issue. There is still technically a current though, and although like you I'm not convinced it's more power than the total of a 0% THD circuit of the same real power, arguing with inspectors has never been something I've found to be a profitable use of my time.

ADDIT: I should add that I've worked in over thirty states and have been required in some jurisdictions to provide neutral calculations, which is basically pulling numbers out of my ass and writing down calculations based on those numbers to make someone feel like he's accomplished something. So counting neutrals as current carrying conductors could be a LOT worse! (Assuming those jurisdictions even make the locals jump through those hoops.)
 

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I'd suspect that MWBC's in residential due to the Arc fault regs as well as the current crop of freshly minted dunces they're more trouble than they're worth?

On many contracts sharing neutrals is prohibited now by the specs, probably due to the high harmonics problem which you say is now under better control?
 

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Technically the only way that a grounded conductor is a neutral is if the load is balanced and thus it is not considered a current carrying conductor. A grounded conductor is a neutral if it has 0 current.
Dennis Alwon

By definition
"Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions."

The language which is underlined and in bold typeface is a crucial part of the definition. For decades the CMP refused to use the term neutral in the code because they couldn't get agreement on what that word meant. By dint of a lot of pressure from engineers and field practitioners of all types they finally gave in and defined it. Prior to that the term of art was "the identified conductor" because that was what was always true about the conductor in question. Although the means of identification varies by use and conductor type it is always identified. When they finally defined Neutral Conductor they dropped the definition of Identified Conductor.

Tom Horne
 

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Due Dilligence: OK, I've checked Article 100, Googled it and checked here on Electrician Talk as well, and it's still not absolutely clear to me (and apparently others) whether the neutral is considered Current Carrying. Some key points I've found are:
  • It does carry current, but is not current carrying conductor (or something like that),
  • and, Yes it is a Current Carrying Conductor, but doesn't always carry current,
  • there are many references to NEC 310.15(B)(4)...which doesn't exist anymore...Whatever.
I'm neck deep in studying Table 310.16 (through Jade Learning, which is excellent), and the values for allowable ampacity need to be modified for conditions such as ambient temperature, number of conductors in a raceway or cable, or other conditions of use. And, as many others say..."it's clear as mud" whether NEC considers the neutral to be a Current Carrying Conductor. What say you all? Edit: I just found it in the 2020 NEC Handbook. Section 310.15(E) reminds us that neutral conductors in some cases, is NOT considered current carrying. From where I'm standing, it looks like in all cases but one, is the neutral considered current carrying. 310.15(E) Neutral Conductor. Neutral conductors shall be considered current carrying in accordance with any of the following:
  1. A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(C)(1).
  2. In a 3-wire circuit consisting of tho phase conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system, a common conductor carries approximately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying the provisions of 310.15(C)(1).
  3. On a 4-wire, 3-phase wye circuit where the major portion of load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor.
Additional Commentary text: Nonlinear loads on 3-phase circuits can cause an increase in neutral conductor current.
Yes a neutral Carries the unbalanced current of the system it is 100%-2000% a current carrying conductor
 

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Once again... because the neutral only carries the imbalance, the heat generated by the full set of conductors (including the neutral) is similar to a circuit fed by hot conductors alone (no neutral) that's why code doesn't count it in the de-rate calcs for a raceway.

It costs an engineer practically nothing to make a specification for dedicated neutrals, larger wire, or a larger conduit. The contractors and customers can fight over the price. :p
 
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